1. Field of the Invention
The present invention relates to an automated centrifuge system, and more particularly, to an automated centrifuge system for automatically centrifuging liquids containing biological materials such as nucleic acids using a conventional centrifuge.
2. Description of the Prior Art
Centrifugation is a typical technique most frequently used in experiments in the fields of biology and medicine, and a centrifuge is utilized in almost all biological laboratories.
The centrifuge is a machine for performing separation, purification and concentration of biological materials having different ingredients or specific gravities, which are included in test tubes, under the action of centrifugal force generated by rotation of a rotor mounted with the test tubes. The centrifuge is used to separate liquids having different specific gravities from one another or solid particles from the liquids containing the particles. Performance of the centrifuge is determined based on a ratio of a centrifugal force to a gravitational force, which is called a centrifugal effect. That is, the centrifugal effect is expressed as (centrifugal acceleration)/(acceleration of gravity). Since magnitude of the centrifugal force is defined as (mass)xc3x97(radius of rotation)xc3x97(square of angular velocity), the centrifugal effect is determined according to a rotational speed and radius of rotation of the centrifuge. Further, the centrifuge is categorized into the following three types according to the centrifuge speed: a low speed centrifuge of which rotational speed is lower than 100 rpm, a high speed centrifuge of which rotational speed is around 10,000 rpm, and an ultra-high speed centrifuge of which rotational speed is greater than 100,000 rpm.
As equipment for completely automating a centrifuging operation using any one of various centrifuges, some equipment such as AutoGeneprep 960 available from Autogen, Inc. in Framingham, Mass., U.S.A. and Genesis available from Tecan Group AG in Maennedorf, Switzerland have been brought into the market. However, the equipment is very restrictive in that some specific centrifuges, liquid handlers for exclusive use in the specific centrifuges, and robots must be placed onto respective desired positions which manufacturers of the automated equipment have already determined. Further, test tubes or microplates specified by the manufacturers should be utilized. Thus, an arbitrary centrifuge hardly can be used. Therefore, there are problems in that it is difficult to use the automated equipment for a specific purpose a user wishes to achieve and the equipment cannot be used together with a novel machine such as a newly developed liquid handler.
Furthermore, the following characteristics of centrifugation make it difficult to develop an automated centrifuge system in which a general centrifuge and general devices related thereto are used. That is, since angular positions of the rotor mounted with the test tubes including samples, which will be centrifuged or have been already centrifuged, are random before start of or after completion of the centrifugation, position information on placement of the respective samples cannot be easily obtained. In addition, in a case where a protective cover for preventing inadvertent outflow of the samples is further provided at the rotor mounted with the test tubes including the samples therein, an operation of automatically opening and closing the protective cover makes automation of the centrifugation still more difficult.
Moreover, in a field of the automation industry for recognizing a target object placed on an arbitrary position, a fixed vision camera is generally installed above the target object so as to determine the position of the target object. However, the vision camera is expensive and has difficulty in performing three-dimensional measurement. Further, complex vision software, a computer, and the like would be required. Therefore, it is not adequate for experiments in a laboratory or processing of a small quantity of samples.
In the meantime, in a case where the centrifugation is performed using the microplate or some types of test tubes, the centrifuge other than the ultra-high speed centrifuge of which rotational speed is greater than 100,000 rpm is generally used. Thus, rotational balance of the centrifuge is not critical. Further, the protective cover for preventing the outflow of the samples is not provided in such a case. Therefore, the automated operation related to the opening and closing of the protective cover can be negligible.
The present invention is contemplated to solve the above problems in the prior art.
In particular, the present invention places great importance on automation of a process of recognizing the positions of microplates or test tubes before start or after completion of centrifugation, which was a major obstacle to an automated centrifugation, when a multi-joint robot and a general centrifuge are used together in a state where they are disposed close to each other. That is, the present invention is characterized by a process of automatically recognizing the positions of the test tubes in tube holes of a rotor of the centrifuge or the microplates in swing buckets connected to the rotor so as to correctly handle the microplates or the test tubes.
Further, the present invention performs automated centrifugation through a process of recognizing correct positions of the test tubes, the microplates or the like by using inexpensive optical fiber photoelectric sensor or laser displacement measurement sensor instead of the vision camera which is expensive and of which control is complicated.
Accordingly, an object of the present invention is to provide an automated centrifuge system by which a process of centrifuging samples can be automatically performed in a general centrifuge by automatically and more efficiently determining positions of test tubes or microplates in the general centrifuge using combination of a general laser displacement measurement sensor or optical sensor and a relevant marker and a multi-joint robot with at least three joints.
According to an aspect of the present invention for achieving the above objects, there is provided an automated centrifuge system for automatically centrifuging liquids containing biological materials such as nucleic acids in accordance with predetermined procedures, comprising: a centrifuge including a rotor in which at least two swing buckets with at least two microplates mounted thereon are provided so as to perform centrifugation of the liquids, a multi-joint robot with at least three joints which includes a gripper attached to a final arm thereof and fingers attached to the gripper, and a controller for controlling the predetermined procedures and the operation of the robot. Furthermore, the centrifuge and the multijoint robot are disposed close to each other on a rigid bottom plate; a position detection sensor is attached to the gripper or one for fingers, at least one marker is attached at a predetermined position on a central frame of the rotor, the predetermined position is spaced apart from a rotating shaft of the rotor by a predetermined radial distance; and the controller causes the gripper to be moved so that the sensor is placed onto a circumference of a circle having a radius equal to the predetermined radial distance and the gripper to be moved around an axis of the rotating shaft of the rotor so that the sensor can detect a position of the marker, thereby automatically performing the predetermined procedures through the detection of positions of the microplates mounted to the swing buckets of the centrifuge.
According to another aspect of the present invention, there is also provided An automated centrifuge system for automatically centrifuging liquids containing biological materials such as nucleic acids in accordance with predetermined procedures, comprising: a centrifuge including a rotor in which a plurality of tube holes for receiving a plurality of test tubes with the liquids contained therein are formed at an equiangular interval on a circumference of a circle having a predetermined radius from a rotating shaft of the rotor, a multi-joint robot with at least three joints which includes a gripper attached to a final arm thereof and a finger attached to the gripper, and a controller for controlling the predetermined procedures and the operation of the robot. Furthermore, the centrifuge and the multi-joint robot are disposed close to each other on a rigid bottom plate; a sensor for use in position detection is attached to the gripper or finger, at least one marker is attached at a predetermined position on a central frame of the rotor, the predetermined position is spaced apart from a rotating shaft by a predetermined radial distance smaller than the predetermined radius; and the controller causes the gripper to be moved so that the sensor is placed onto a circumference of a circle having a radius equal to the predetermined radial distance and the gripper to be moved around an axis of the rotating shaft of the rotor so that the sensor can detect a position of the marker, thereby automatically performing the predetermined procedures through the detection of positions of the respective test tubes inserted into the tube holes of the rotor of the centrifuge.